Loading...
Please wait, while we are loading the content...
Similar Documents
Comment on the “Analysis of the State of Stress During the 1997 Earthquake Swarm in Western Bohemia” by A. Slancová and J. Horálek (Studia geoph. et geod. 44(2000), 272–291)
| Content Provider | Semantic Scholar |
|---|---|
| Author | Vavryčuk, Václav |
| Copyright Year | 2000 |
| Abstract | Horalek et al. (2000) show that the earthquakes of the January 1997 earthquake swarm are grouped into several types according to their waveforms, but two of them are predominant. The events of these types were denoted as the A and B events. Fischer and Horalek (2000) located the swarm events and found that the foci of the A and B events form clusters with different geometries (see Fig. 1). Horalek et al. (2000) and Dahm et al. (2000) selected 70 well-recorded events and calculated their moment tensors by inverting the Pand S-wave amplitudes. They found that the A and B events also differ in their mechanisms: the A events are oblique normal, while the B events are oblique reverse. Obviously, we are faced with the question, which of the two nodal planes in the mechanisms is the fault plane. SH try to answer this question on the basis of stress analysis. They applied this rather unreliable method (see Sec. 2) ignoring another more natural approach: a comparison of the geometry of the foci clusters with the focal mechanisms (see Lund and Slunga, 1999). The latter approach is, in particular, very suitable for application to swarm earthquakes, because of the high number of foci located. I performed this comparison and the results are shown in Fig. 2. For both types of events, one of the nodal planes almost perfectly coincides with the fault plane calculated by Fischer and Horalek (2000) from the clustering of foci. It coincides even with the orientation of the faults obtained by simple visual interpolation of the foci clusters (see Figs 1 and 2). Therefore, Figure 2 indicates that the A and B events are related to two nearly perpendicular fault systems. The strikes of the fault planes for the A events lie in the interval (290°, 315°) and for the B events in the interval (20°, 60°). This result, however, contradicts one of the conclusions made by SH. |
| Starting Page | 614 |
| Ending Page | 619 |
| Page Count | 6 |
| File Format | PDF HTM / HTML |
| DOI | 10.1023/A:1021884222133 |
| Alternate Webpage(s) | https://www.ig.cas.cz/wp-content/uploads/2018/02/sgg2000.pdf |
| Alternate Webpage(s) | https://page-one.springer.com/pdf/preview/10.1023/A:1021884222133 |
| Alternate Webpage(s) | https://doi.org/10.1023/A%3A1021884222133 |
| Volume Number | 44 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
